Either I am not understanding somethng or Rifle is kinda bad as off-hand without Chakram

Several abilities cause you to additionally strike with off-hand. Regardless of distance. This kinda makes the weapon whose only effect is increased range bad as off-hand.

Let's say you have Pistol. You use Q to double-attack, both healing yourself and slowing/cleaving/enhancing chakram damage. If the target is already in range of Q they are hit and Rifle doesn't do anything extra.

Or maybe you have Flamethrower. You flame multiple targets (like Vayne Main). Once again, in addition to dealing ability damage + attack damage you heal/slow/enhance chakram damage. But the Rifle once again doesn't do anythign extra since they are guaranteed to be hit regardless of distance If they were already hit by the flame.

So I'd say only Chakram, assming the turret's range is increased, benefits from Rifle off-hand. It's possible in majority of cases, players will maintain classic order, always expending main-hand first, which means they will only get Rifle off-hand with Chakram, so maybe that's why there is no change, but If someone wanted to play with the order, Rifle off-hand seems bad to me.